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1. Field of the Invention
The present invention relates to light flash recovery. More particularly, the present invention relates to a method and apparatus for using a flash recovery timer and warning device to monitor flash recovery.
2. General Background of the Invention
Ordinary work and household illumination levels provide little challenge to the vision tissue of the healthy eye to maintain continuous vision. Brighter light exposure such as looking at fluorescent tubes or bright flashes such as camera flashes can temporarily xe2x80x9cflash-blindxe2x80x9d or xe2x80x9csnow-blindxe2x80x9d the central retina. In healthy eyes, the central vision recovers within a few seconds from a single brief bright light exposure.
In the presence of eye diseases that produce either edematous swelling of the central retina or deterioration of some of the tissues in the central retina, the amount of time required to recover from such brief bright light exposure is prolonged, in some cases greatly prolonged. Examples of eye diseases that can produce prolonged flash recovery times include diabetes related retina disease (diabetic cystoid macular edema) and macular degeneration with macular edema and other changes. These diseases affect millions of Americans.
In the early stages of certain eye diseases, flash recovery times may not be prolonged. With changes or worsening of the disease such as the new appearance of tissue swelling or the appearance of a bad blood vessel with leakage or bleeding, the flash recovery time can be greatly prolonged. The early detection of disease appearing or worsening, which can be warned of by prolongation of flash recovery time, could assist patients in obtaining professional help earlier.
The following patents are incorporated herein by reference: U.S. Pat. Nos.: 4,545,658; 5,080,478; 5,065,767; 4,764,007; 2,247,653; 3,684,355; 2,232,316; and 2,283,769.
U.S. Pat. No. 4,545,658 discloses a portable flash device designed to temporarily xe2x80x9cblindxe2x80x9d the eye, and record the time of recovery to normal.
U.S. Pat. No. 2,283,769 discloses eye testing by placing a bright light in the eyes and temporarily xe2x80x9cblindingxe2x80x9d the person, then measuring the recovery time.
U.S. Pat. Nos. 2,247,653, 5,080,478, 4,764,007 and 3,684,355 disclose devices for testing glare and darkness on the eyes and measuring recovery.
The apparatus of the present invention solves the problems confronted in the art in a simple and straightforward manner. What is provided is an improved flash recovery timer and warning device.
The flash recovery timer of the present invention is equipped with an audible and visual warning signal to provide an instrument that is easy to understand and use. The present invention could assist persons at risk for deteriorating vision, detecting that deterioration early so that the patient can seek appropriate professional help. Early detection by an appropriate eye care professional could result in a much better chance of preserving vision.
The flash recovery timer and warning device of the present invention is preferably a hand-held electronic device using a bright flash to create a temporary glare-type vision blur to the eye to be tested. A target with a display (e.g. letter) and timer determine the amount of time required for the eye to recover after the flash. The device has a voice chip that, in addition to the timer display, warns that the vision recovery time is unusually prolonged and professional help should be sought. Other clinical applications may be useful.
Prolongation of glare or flash recovery time has been recognized for over a century as a sign of trouble with the central retina. There are a number of central retinal problems that can occur in the course of chronic diseases such as macular degeneration and diabetes that can devastate central vision. In some but not necessarily all cases, early detection of these pathologic changes can assist eye care providers in preserving vision.
The Flash Recovery Timer and Warning Device of the present invention provides an easy to use and understand portable office and/or home testing method to give early warning about changes in the functional ability of the eye to recover from bright light exposure.
Many persons despite careful instruction in the doctor""s office, do not follow through, either from lack of understanding or from lack of motivation or perceived need with checking the function of their eyes monocularly at home. This device offers a simple reminder of the importance of home testing. It also offers a simple way of actually performing the test.
The amount of light energy delivered to the ocular surface and macula is below the threshold of damage according to ANSI standards.
A base-line of recovery can be established for each eye either in the doctor""s office or at the time of acquiring the instrument. It will then be very easy for the subject to determine that there has been a change (prolongation) of flash recovery time.
The timer will also have a pre-programmed upper limit recovery time. If that time is exceeded, a warning will sound.
The present invention thus provides a flash recovery timing apparatus of improved construction. The apparatus includes a tubular instrument body having a bore, first and second end portions and a generally cylindrically shaped or tubular wall.
An aperture is provided at the first end portion of the instrument body, a lens being mounted in the aperture.
A display is positioned within the bore at the focal length of the lens so that a patient can focus on the display by looking through the lens.
A strobe or like lighting means is positioned within the bore for generating a bright flash of light within the bore for use during a flash recovery test. A wiring harness is provided that includes one or more switches. One of the switches can be used to activate the strobe. One of the switches can also be used to activate a timer for measuring the patient""s response time of viewing the display after the strobe is activated.
A stop is provided for stopping the timer responsive to the patient""s ability to see the display, thus evidencing flash recovery.
The stop can include a voice activated timer that times the delay between the strobe flash and the patient""s voice activation.
The display is preferably a variable target such as an LCD display that can display different visual images such as different letters or different numbers in sequence. The apparatus can provide a microphone on the instrument body next to the lens for use with the voice activation software carried in the computer.
A power source such as a battery can be a part of the instrument body so that the apparatus is self-contained and can be disposable after the battery has been drained with power.
The apparatus can include a computer that controls operation of the strobe, the display and the timer. The computer can also be used to provide voice recognition software that listens to the patient""s voice through the microphone and talks after a test through a voice chip.
The present invention provides an improved method of measuring a patient""s flash recovery time. The method steps include the providing of an instrument that includes an instrument body with a bore, a viewing aperture at one end of the bore, a strobe in the bore, a timer, a visual display within the bore, a computer and a wiring harness that includes one or more switches.
As part of the method, the patient views the display through the aperture. Using one of the switches, the strobe is fired to generate a light flash inside the bore.
A firing of the strobe simultaneously activates the timer. The patient indicates when the display can be seen after the light flash of step xe2x80x9ccxe2x80x9d thus providing an indication of flash recovery. The timer measures the elapsed time between the flash activation and the patient""s ability to once again view the display.
A computer can be used to provide an audible indication of test failure if the measured elapsed time in seconds for example, exceeds a pre determined acceptable time value.
The visual display preferably changes between the time that the flash is generated and the patient recovers from the flash.
The method contemplates the instrument being provided with a voice chip and the voice chip speaks an audible message that the test has failed.
The method contemplates a microphone that is carried by the instrument body or which interfaces with the instrument body and its computer for listening to the patient""s voice when the test is completed, as when the patient""s flash recovery is complete and the patient is able to view the image. In such a situation, the patient reads the letter and the voice recognition software stops the timer if the patient correctly identifies the displayed letter or number.
The switches that are used as part of the instrument with the method can include an on/off switch and a reset switch. The instrument can include a microphone wherein the computer is voice activated by the microphone and the patient""s voice. Alternatively, the patient can depress a switch to indicate that the display can be seen, thus stopping the timer to indicate that flash recovery is complete. The computer can compare the visual display with the patient""s utterance and determines if the patient has correctly read the display. Thus, the display preferably changes from the time that the test begins until the patient is able to view the LCD display again. For example, a new letter can be displayed a few milliseconds after the strobe has flashed.
Preferably, there are storage means for recording and storing a plurality of the patient""s flash recovery times. The storage means is preferably in the instrument.